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Imec has successfully fabricated implant-free quantum-well (IF-QW) pFETs with an embedded silicon-germanium (SiGe) source/drain. Imec’s second generation of SiGe45% IF-QW pFETs were processed on standard 300mm STI wafers. Compared to earlier IF-QW devices, the raised SiGe and Si substrate are recessed and replaced with a thick SiGe25% epi-layer to form the source/drain electrodes.

The next-generation of multimedia applications will require ICs that are both powerful and low power. One such option is the use of high-mobility channels (ie: SiGe [silicon-germanium] with a high Ge content). Unfortunately, additional scaling of the gate length will require a better electrostatic gate control, and a low variability of the key electrical parameters. Thanks to imec, the IF-QW concept with a buried SiGe channel has been show to meet these requirements while significantly improving the device performance.

Their devices have an excellent short channel control and a record logic performance. A benchmark against various competing technologies showed competitive results. In addition, the device performance was also demonstrated at low operating voltages. Their results prove that this device architecture is a viable option for the 16nm technology node and beyond. Imec has also developed process modules that minimize local variations and maximize the device performance.

This has resulted in an excellent short channel control, with a drain induced barrier lowering of ~110mV/V at 35nm-LG and a record 1mA/µm-Ion at -1V. For lower operating voltages, an increased performance was demonstrated. The devices were benchmarked at various operating voltages against state-of-the-art technologies such as SOI nFETs or SiGe-FET, showing at least equivalent results. The results show that SiGe IF-QW devices with embedded source drain form a promising architecture for integration on bulk Si, from the 16nm node onwards.